Yes confirmed the sad news with a post on Facebook. "It's with the heaviest of hearts and unbearable sadness that we must inform you of the passing of our dear friend and Yes co-founder, Chris Squire. Chris peacefully passed away last night in Phoenix, Arizona," the band wrote.

"For the entirety of Yes' existence, Chris was the band's linchpin and, in so many ways, the glue that held it together over all these years. Because of his phenomenal bass-playing prowess, Chris influenced countless bassists around the world, including many of today's well-known artists. Chris was also a fantastic songwriter, having written and co-written much of Yes' most endearing music, as well as his solo album, Fish Out of Water," the post continued.

Earlier this year, Squire — the sole member of Yes to appear on all the group's studio albums — revealed that he was diagnosed with acute erythroid leukemia. The illness forced the bassist to bow out of Yes' co-headlining summer tour with Toto.

"This will be the first time since the band formed in 1968 that Yes will have performed live without me," Squire said in a statement (via Rolling Stone). "But the other guys and myself have agreed that Billy Sherwood will do an excellent job of covering my parts and the show as a whole will deliver the same Yes experience that our fans have come to expect over the years."

Yes formed in 1968 when Squire met singer Jon Anderson in London. The group released its self-titled debut that same year.